ABB Relion 670 Series Applications Manual page 356

Section 13
Control
=
I
C
3
EQUATION1982-ANSI V1 EN-US
In this way the measured LV currents can be adjusted so that the capacitor bank current will not
influence the calculation of the circulating current.
Three independent capacitor bank values Q1, Q2 and Q3 can be set for each transformer in order
to make possible switching of three steps in a capacitor bank in one bay.
Power monitoring
The level (with sign) of active and reactive power flow through the transformer, can be monitored.
This function can be utilized for different purposes for example, to block the voltage control
function when active power is flowing from the LV side to the HV side or to initiate switching of
reactive power compensation plant, and so on.
There are four setting parameters
TR1ATCC (90) function blocks PGTFWD, PLTREV, QGTFWD and QLTREV. When passing the pre-set
value, the associated output will be activated after the common time delay setting
The definition of direction of the power is such that the active power P is forward when power
flows from the HV-side to the LV-side as shown in figure 172. The reactive power Q is forward
when the total load on the LV side is inductive ( reactance) as shown in figure 172.
Pforward
Qforward
(inductive)
ANSI06000536 V2 EN-US
Figure 172: Power direction references
With the four outputs in the function block available, it is possible to do more than just supervise a
level of power flow in one direction. By combining the outputs with logical elements in application
configuration, it is also possible to cover for example, intervals as well as areas in the P-Q plane.
Busbar topology logic
Information of the busbar topology that is, position of circuit breakers and isolators, yielding
which transformers that are connected to which busbar and which busbars that are connected to
each other, is vital for the Automatic voltage control for tap changer, parallel control function
TR8ATCC (90) when the circulating current or the master-follower method is used. This
information tells each TR8ATCC (90), which transformers that it has to consider in the parallel
control.
350
V
B
×
X
C
HV-side
LV-side
P> , P< , Q> and Q< with associated outputs in TR8ATCC (90) and
IED
ATCC
ANSI06000536-2-en.vsd
1MRK 511 358-UUS A
(Equation 126)
SEMOD159053-251 v4
tPower .
SEMOD159053-259 v3
Application manual